Fulvic Acid. Ii. Interaction With Metal Ions

Summary Evidence is presented, based on sequestration, chemical behaviour, ultra‐violet and infra‐red spectroscopy, to indicate the formation between the non‐cationic fraction of fulvic acid and a variety of transition metal ions, of stable soluble complexes and also of insoluble complexes over the complete pH range. The soluble complexes formed under alkaline conditions are negatively charged. The fulvic material is very effective in competing with other ligands for the metal ions. Mechanisms for the flocculation of the soil organic matter in the presence of heavy metal ions are discussed. The formation of inert complexes between cobalt and the fulvic material is also demonstrated and its implications to the study of metallo‐organic complexes are discussed.